In a Long Term Evolution (Long Term Evolution, LTE) system, before receiving or sending service data, a user equipment (User Equipment, UE) is required to acquire downlink control information (Downlink Control Information, DCI) configured by an evolved NodeB (Evolved NodeB, eNB) for the user equipment, and the DCI is carried by a physical downlink control channel (Physical Downlink Control channel, PDCCH). One PDCCH is formed by aggregating one, two, four, or eight continuous control channel elements (Control Channel Element, CCE). Each aggregation level (aggregation level) corresponds to one search space (as shown in Table 1), and the aggregation level indicates how many CCEs are aggregated to form one PDCCH. The search space is a to-be-detected PDCCH set of the UE. There are 2 types of search space: common search space (Common search space) and User Equipment specific search space (UE specific search space).
TABLE 1Search spaceNumber of Aggregation Number PDCCHs to Typelevelof CCEsbe detectedUE specific 166search space21264828162Common 4164search space8162
The related art has the following defects.
In a carrier aggregation (carrier aggregation, CA) system, a user equipment may use multiple component carriers (component carrier, CC) to carry data channel at the same time. One DCI is configured for scheduling data carried on one component carrier or indicating power control and different DCI is carried by different PDCCHs. When the PDCCHs are carried by one component carrier for carrying a control channel or by a small number of component carriers for carrying control channels, since the size of a search space defined in the related art is limited, the blocking probability of PDCCH scheduling is very high.